1. Technical Field of the Invention
The present invention relates to a method for preparing a pharmaceutical or cosmetic formulation, preferably an ointment, containing an active agent or a microdosed dispersible active principle.
2. Description of Background and/or Related and/or Prior Art
It is known that the manufacture of preparations with a low active principle concentration entails problems of homogenizing the active principle in its excipients. This is because microdosed active principles encounter dispersion heterogeneity problems when they are mixed with large volumes of excipients.
These preparations normally must be subjected to an intermediate dilution phase in order to obtain products with a low active principle concentration.
An additional problem arises when the active principle belongs to a class of toxic products. In this case, the handling not only takes a long time but also becomes dangerous, which significantly increases the risks of accident.
Added to this is the problem of transporting the toxic product while keeping it protected it from light and oxidation phenomena.
One example of preparations made by these methods are ointments. These are preparations for external use, intended to be topically applied directly on the skin and so must be in a predetermined range of viscosities which can be applied to the skin. If the active principle in the ointment is a solid, it will be sprinkled as finely as possible and incorporated into the ointment by the principle of geometrical dilution.
Geometrical dilution involves a series of dilution steps. It starts with the active principle being incorporated into an amount of excipient approximately of equal size. A second amount of excipient, approximately equal to the first mixture that has been formed, is added and then mixed.
This procedure with dilution steps is carried out until all of the excipient has been used, so as to obtain the intended concentration of active principle.
The various products involved in the manufacture of the ointment are generally mixed together by melting over a water bath, followed by stirring until the mixture has cooled. In this case, the active principle will be incorporated at a suitable stage. A long, drawn out iterative process is therefore required to ensure homogeneity.